Pocket clip



April 3, 1962 E. DJTHOMPSON ETAL 3,027,613

POCKET CLIP 2 Sheets-Sheet 1 Filed May 6, 1959 ELMER DALE THOMPSON 5 LEW/5 CARROLL HANSEN April 3, 1962 POCKET CLIP Filed May 6, 1959 2 Sheets-Sheet 2 A F/G. /4

FIG. /0

INVENTOR.

ELMER DALE THOMPSON 8 LE W/S CARROLL HANSEN 3,627,613 PGEKET QLIP Eimer Date Thompson and Lewis Carroll Hansen, Fort Madison, Iowa, assignors to W. A. Sheaifer Pen Company, Fort Madison, Iowa, a corporation of Delaware Fiied May 6, 1959, Ser. No. 811,414 Claims. (CI. 24-11) This invention relates to clips and has special reference to a pocket clip having a flexible arm adapted to provide uniform stress along its flexing length.

In particular, this invention relates to a clip having an arm, mounting means on one end of the arm, and contact means on the other end of the arm, the cross section of the arm being of such size and shape as to progressively increase in resiliency with the distance from the mounting means to provide uniform stress in the arm along substantially its entire length upon application of transverse pressure to the contact means.

A clip of the type usually provided on a writing instrument or the like, includes a resilient arm having mounting means on one end thereof and contact means, generally of a semi-spherical configuration, on the other end. The mounting means may consist of a pair of deformable ears, an annular ring, or the like, rigidly secured to the instrument in such a manner that the contact member or means carried at the free end of the arm normally is urged toward and positioned against the body of the instrument. The resilient arm, however, permits limited transverse movement of the contact member in a direction away from the body to slidably receive therebetween the top outer edge of the shirt or coat pocket in which the instrument may be carried. The resilient arm, of course, acts to maintain a constant pressure on the pocket material.

It has been observed that when the arm of the usual clip is flexed away from the body of a writing instrument or the like the resultant bending stress is distributed unevenly throughout the arm, the maximum stress generally being created in the area adjacent the mounting means and decreasing to a comparatively low value at the free end. In other words, a dis-proportionately large percentage of the flexing occurs in one small area of the clip arm. Accordingly, after extensive use or as a result of severe distortion the arm may fail either as a result of breakage in the area of maximum stress or because the elastic limit of that area has been exceeded.

As applied to clips, it is understood that the elastic limit is the point of distortion or flexing beyond which the material of the aim, particularly the material in the area of maximum stress, will take a set and fail to return to its original condition. Exceeding the elastic limit, of course, will result in a clip which fails to exert sufficent pressure to securely hold a writing instrument or the like in a coat or shirt pocket. And this is a particularly vexing problem because of the danger of inadverent loss of an instrument which may be quite valuable from the standpoint of replacement cost and/ or sentiment.

Even though the usual type of clip has been used commercially for many years the above problems have long been recognized by individuals skilled in the art, and numerous suggestions have been made for their solution. For example, it has been proposed to provide a substantially rigid clip arm and furnish the necessary resiliency by means of a separate spring element mounted within and arranged to resiliently hold the clip to the writing instrument body. Such a construction is disclosed in US. Patent 2,473,690. While this type of spring mounted clip has enjoyed wide commercial success, it has certain limitations due to manufacturing costs and, in some cases, lack of space within the cap or barrel of a writing instrument. This space limitation is particularly noticeable 31921613 Patented Apr. 3, 1962 ice with respect to the present day retractable ball point pen, which does not require a separate cap to protect the writing point.

Accordingly, one object of this invention is the provision of a clip in which the arm thereof is not subject to failure due to the concentration of bending stress in one limited area thereof.

Another object of this invention is to provide a clip in which the arm thereof is stressed uniformly throughout substantially its entire length upon the application of transverse pressure on its free end.

A further object of this invention is a provision of a clip having a resilient arm in which the stress at any given cross section is substantially equal to the stress in any other given cross section upon the application of transverse pressure to the contact member.

A still further object of this invention is to provide a clip having a resilient arm which may be flexed to accommodate practically any thickness of the material of the type generally used for clothing, without the elastic limit of the arm being exceeded.

Yet another object of this invention is the provision of a one piece clip which is inexpensive to manufacture but which is efiicient and durable and does not require undue care on the part of the user.

Further and additional objects of this invention will be apparent from the following description, when taken with the accompanying drawings in which: 7

FIGURE 1 is a top plan view of a clip constructed in accordance with a preferred embodiment of this in vention;

FIGURE 2 is a side elevational View of the clip of FIGURE 1;

FIGURE 3 is a cross sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is a cross sectional view taken along the line 4-4 of FIGURE 1;

FIGURE 4A is an enlargement of FIGURE 4, containing reference characters explained hereinafter;

FIGURE 5 is a cross sectional view taken along the line 5-5 of FIGURE 1;

FIGURE 6 is a longitudinal sectional view of another embodiment of this invention;

FIGURE 7 is a cross sectional view taken along the line 7-7 of FIGURE 6;

FIGURE 8 is a cross sectional view taken along the line 8-3 of FIGURE 6;

FIGURE 8A is an enlargement of FIGURE 8, containing reference characters explained in detail here inafter;

FIGURE 9 is a cross sectional view taken along the line 9-9 of FIGURE 6;

FIGURE 10 is a top plan view of a third embodiment of this invention;

FIGURE 11 is a longitudinal sectional view of the clip of FIGURE 10;

FIGURE 12 is a cross sectional view taken along the line 12-12 of FIGURE 11;

FIGURE 13 is a cross sectional view taken along the line 13--13 of FIGURE 11; and

FIGURE 14 is a cross sectional view taken along the line 14-44 of FIGURE 12.

Referring now to the drawings and particularly to FIGURES 1 through 5 thereof, there is provided a one piece pocket clip 20 which may be fabricated from flat stock and which includes a resilient arm 21 having mounting means generally designated at 22 on one end thereof, and contact means 23 on the other end.

The stock, preferably of constant thickness, may be selected from the usual type of material utilized in manufacturing clips, such as spring brass or the like, and is processed in a manner well known in the art. Briefly,

3 the processing includes stamping a blank from flat stock material and subsequently subjecting the blank to a series of drawing operations to contour the arm and to form the mounting means and contact means at opposite ends thereof.

Although any one of a number of mounting arrangements may be employed, in this embodiment there is provided a pair of spaced ears 22a of a type well known in the art. The ears are adapted to enter a pair of corresponding slots in a writing instrumentholder (not shown), whereafter they may be deformed against the interior wall of the holder to insure proper retention of the clip 20.

The contact member 23 is of the usual type, being formed as an integral part of the clip from a plurality of projections at the free end of the arm 21.

As can best be determined from the cross sectional views 3, 4, 4A and 5, the arm 21 of the clip is formed of flat material of constant thickness, and includes base portions 24 and 24a, 21 flat raised center portion 25 extending longitudinally of the arm, and connecting portions 26 and 26a. In effect, these various portions form a plurality of substantially rectangular sections, each of which decreases uniformly either in height or width with the distance from the mounting means 22. Thus, the overall height and width of the arm 21 decreases uniformly with the distance from the mounting means 22 and, as explained in more detail hereinafter, when the arm is flexed in the usual manner the stress at any given cross section is substantially equal to the stress in any other given cross section. In other words, the stress is essentially constant throughout the bending length of the arm.

Accordingly, the load is distributed evenly throughout the arm and the heretofore common difliculty of failure in a certain area of the arm is eliminated. At the same time, the potential amount of deflection in the arm is increased greatly since one area is not subject to failure before the balance of the arm has deflected to its maximum extent.

While this invention is not to be limited to a clip having an arm made of a specific material or having any particular appearance, size, or shape, it is understood that a certain criteria must be employed in order to establish for a specific material and a general design the proper relationship of the area and form at any cross section of the arm to that in any other cross section. For this purpose, the clip arm 21 is treated as a cantilever beam, in that one end is adapted to be fixedly secured to the body of a writing instrument of the like by the mounting means 22, with the other end free to deflect in a transverse direction away from the body.

As can be determined from various references, a cantilever beam may be adapted to provide uniform or constant stress throughout its bending length, and in such beams the section modulus is proportional to the bending moment. In other words, the moment of inertia of a given cross section of the beam, divided by the distance from its neutral axis to the extreme fiber, will result in a quotient which varies directly with the distance from the point of load to the given cross section. Therefore, in order to establish the relative proportions throughout the clip arm 21, a formula for determining the maximum stress at any given cross section of a cantilever beam is used. Such a formula is given on page 300 of the 2nd edition of Mechanics of Materials (Laurson Cox), as follows:

Formula N0. 1

where S=stress in pounds per square inch .P=load in pounds X =distance in inches from the load to the given cross section C=distance in inches from the neutral axis to the extreme fiber I =moment of inertia in inches of the given cross section about the neutral axis As pointed out heretofore, large deflection is desirable in the arm of a clip and since the deflection or maximum stress is inversely proportional to the moment of inertia (see the above formula) the moment of inertia of the cross sections of the arm should be kept as low as possible while still maintaining a constant stress relationship. This condition is most easily satisfied by a clip arm of solid decreasing cross section, but for reasons of manufacturing ease and economy, it is desirable to form the clip arm 21 from flat material of constant thickness.

In using the above formula, identified as No. l, S or the maximum stress figure remains constant, and is determined by the type of material chosen for use in fabricating the clip. For example, a desirable clip material such as spring brass has a maximum stress or elastic limit figure of 40,000 to 60,000 pounds per square inch. P or the load in pounds would vary somewhat, dc-

, pending upon the manufacturer, but it has been found that a load of 1 /2 pounds is satisfactory as a maximum designed load. X is dependent, of course, upon the particular cross section selected for use in the formula, and is readily determined by a simple measuring operation. However, determination of the C and i factors is somewhat more involved. As an example of the meth- 0d of calculating these two factors, reference will now be made to FIGURE 4A in which, for convenience, the dimensions of the various portions of the arm are defined by certain arbitrarily select reference characters.

Page 358 of Machinerys Handbook (14th edition) gives the formula for finding the moment of inertia of a rectangle about a line through its center and parallel to its base, the formula being:

Formula N0. 2

where I=moment of inertia b=base of rectangle h=height of rectangle Moment of Inertia Arm Portion The true moment of inertia of the cross section around its neutral axis cannot be found merely by adding the moment of inertia of the various portions, however, as each portion is calculated around its own axis or center of gravity. Therefore, it is necessary to determine the moment of inertia of the cross section around its neutral axis or center of gravity. For this purpose, it is first necessary to find the total moment of inertia of the various portions around a common axis, designated as axis a in FIGURE 4A, which can be determined from a further formula given on page 313 of Machinerys Handbook, which states the following:

Formula N0. 3

If the moment of inertia I of a solid or surface with respect to an axis through its center of gravity is known, then the moment of inertia with respect to any parallel axis at a distance a from the axis through the center of gravity is:

I,,=I=Axa where I,,=moment of inertia around a parallel axis I=moment of inertia around the neutral axis A=mass or area of the figure or cross section a=distance from neutral axis to the parallel axis Therefore, the total moment of inertia of the cross section at line 4--4 of the arm 21 around the axis a is:

Since the axis a is not the neutral axis of the cross section, the neutral axis must be found. Page 310 of the cited Machinerys Handbook reference indicates that the neutral axis can be determined by the formula:

Formula N0. 4

where =neutral axis of cross section M, N, etc.=each indicates area of one rectangular portion m, n, o etc.=each indicates the distance from the axis a to the center of gravity of the individual rectangular portions Thus, the neutral axis 1 of the cross section of the arm 21 at line 4--4 is:

W2T+m+W1h Generally, the 5 figure is indicative of the distance from the neutral axis of the cross section to its extreme fiber, and in such case may be employed as C in the above constant stress formula (Formula No. 1). However, in this configuration, a variation has been noted and for this reason it is preferred that for each calculation the figure for H be subtracted from the height or h and the answer thus obtained used in the constant stress formula if it is greater than ij. In other words, C is the greater of either or the height h minus 1].

Referring to the constant stress formula, the last remaining factor is I. book reference, page 313, it is determined that the moment of inertia of the cross section around its neutral axis E may be calculated from the formula:

Formula No. 5

Iy=Ia -g7 A where I =mornent of inertia around the neutral axis Ia=moment of inertia around the common axis a 7=neutral axis A=area of cross section Thus, the moment of inertia of the cross section at line 4-4 of the arm 21 around its neutral axis is:

From the cited Machinerys Hand- While the above description indicates that the clip is preferably fabricated from flat stock, it is understood that a casting or similar process may be employed.

The embodiment illustrated in FIGURES 6 through 9 includes a one piece clip 30 having an arm 31, the cross section of which more nearly approximates a rectangular figure. As in the case of the first embodiment, the arm 31 uniformly decreases in overall height and width and progressively increases in resiliency with the distance from the mounting means 32, which includes a pair of deformable ears 32a, and terminates at the other end in an integral contact member 33. The clip 30 preferably is made of a suitable material such as spring brass, berillium copper, or the like, and formed from a flat stock of constant thickness.

The arm 31 consists of a longitudinal extending rectangular top portion 34, and two longitudinally extending lower rectangular portions 35 and 35a. The lower portions 35 and 35a are connected with the top portion 34 by means of curved semi-circular portions 36 and 36a. As is observed from FIGURES 7, 8 and 9 of the drawings, the 3 rectangular portions and the connecting portions uniformly decrease in width and diameter respectively with the distance from the mounting means 32. This effects a uniform decrease in overall height and width and a progressive increase in resiliency of the arm 31 with the distance from the mounting means 32. This increase in resiliency, of course, is calculated by means of the constant stress formula given previously in order to insure that the stress is uniform along substantially the entire length of the arm 31 upon the application of transverse pressure to the contact member 33.

The opening 37 between the two lower rectangular portions 35 and 35a of the cross section, is utilized in cooperation with the above identified arm portions as a means of varying the section modulus in order to control the stress. This particular shape also is advantageous in that it has no sharp exposed edges to rub on and cause wear of the material of a pocket with which it may be used.

The relative proportions of the various portions of the clip arm 31 are determined by the constant stress formula given previously, Formula No. 1. However, since an added element of the semi-circular portions 36 and 36a is introduced, it is believed desirable to briefly explain the manner of finding the factors C and I in the constant stress formula.

As described above, the factor S is determined by the particular material chosen for use in the clip; the factor P has been selected as 1 /2 pounds; and, X is the measurable distance from the contact member 33 to the given cross section.

Referring now to FIGURE 8A and by utilizing Formula No. 2, it is found that the moments of inertia of the 3 retangular portions 34, 35 and 35a about lines through their centers are And the moment of inertia of the 2 semi-circular connecting portions 36 and 36a, which are considered as a circular figure for the purpose of this computation, is .O49(D -d Reference is made to page 361 of the cited reference as the basis for this figure.

Before the moment of inertia figures may be substituted in the constant stress formula, however, it is necessary to find the neutral axis of the cross section and the moment of inertia of the cross section around that axis. This may be accomplished first by finding the moment of inertia of the rectangular portions 34, 3S and 35a around a common axis, preferably the axis a which connects the semi-circular portions 36and 36a. Based on Formula 7 No. 3, the moment of inertia of the 3 rectangular portions around the common axis is as follows:

W W T D T z wwewarm Thus, the total moment of inertia of the cross section around axis a is equal to:

Therefore, for this configuration the factor C of the constant stress formula is According to Formula No. 5, the moment of inertia of the cross section around its neutral axis is:

(W +W )T+.7854(D d This figure is used as I in the constant stress formula. The embodiment of FIGURES through 14 discloses a one-piece metallic clip 46 having an arm 4-1 which is composed of a top portion 42 and downwardly extending rectangular side portions 3 and 43a. Integral mounting means 44, including a pair of deformable ears 45, is formed at the upper end of the clip arm 41, with a contact member 46 being formed at the opposite end. The clip is preferably made of material of constant thickness and of a type generally utilized for the manufacture of flexible clips.

The top portion 42 is substantially of constant width, as opposed to the tapering arms of the previous embodiment. Thus, it is necessary to depend upon the downwardly extending side portions 43 and 43a to control the stress factor in the arm when it is flexed. And such control is obtained by progressively decreasing the height of the portions 43 and 43a with the distance from the mounting means 44 in accordance with the constant stress formula, the application of which is given in detail with respect to the first two embodiments. It is believed that it is not necessary to repeat this procedure, since the same basic formulae are employed in each instance.

It is understood that although only 3 embodiments are illustrated and described herein, the invention is not to be limited to the embodiments described above, but it is contemplated, by the appended claims, to cover any such modifications which fall within its true spirit and scope.

We claim:

1. A pocket clip of the character described, including an arm, mounting means on one end of said arm, and contact means on the other end of said arm, said arm being formed of flat material of constant thickness and having a longitudinal central raised portion, the height of said raised portion and the width of said arm and raised portion uniformly decreasing with the distance from said mounting means, said uniformly decreasing height and width being determined by the formula Maximum stress:

2. A clip of the character described, including an arm, mounting means on one end of said arm, and contact means on the other end of said arm, the cross section of said arm defining a rectangular center portion and at least one rectangular segment formed along each edge of said center portion, the height and width of said arm decreasing uniformly in aggregate cross sectional area and increasing progressively in resiliency with the distance from said mounting means, said uniformly decreasing height and width being determined by the formula PXC I' where S=stress in pounds per square inch P=load in pounds X=distance in inches from the load to the given cross section C=distance in inches from the neutral axis to the extreme fiber l=moment of inertia in inches of the given cross section about the neutral axis thereby providing uniform stress along substantially the entire length of said arm upon the application of transverse pressure to said contact means.

3. A clip of the character described, including an elongate arm, mounting means formed on one end of said arm, and contact means formed on the other end of said arm, said arm being formed of material of substantially constant thickness, the cross section of said arm defining a plurality of integral rectangular portions which decrease uniformly in aggregate area and increase progressively in resiliency with the distance from said mounting means, said uniformly decreasing area being determined by the formula Bending moment Section modulus thereby providing uniform stress along the entire length of said arm upon the application of transverse pressure to said contact means.

4. A clip of the character described, including an arm, mounting means formed on. one end of said arm, and contact means formed on the other end of said arm, the cross section of said arm defining a rectangular raised center portion, a pair of rectangular base portions spaced from said center portion, and a pair of rectangular connecting segments linking said raised center portion and said base portions, the height and width of the said arm decreasing and the resiliency progressively increasing with the distance from said mounting means, said uniformly decreasing height and width being determined by the formula Maximum stress:

where S=stress in pounds per square inch P=load in pounds X =distance in inches from the load to the given cross section C=distance in inches from the neutral axis to the extreme fiber I=moment of inertia in inches of the given cross section about the neutral axis thereby providing uniform stress in said arm along substantially its entire length upon application of transverse pressure to said contact means.

5. A clip of the character described, including an arm, mounting means formed on one end of said arm, and contact means formed on the other end of said arm, the cross section of said arm defining a rectangular top portion having integral with each edge thereof a semi-circular connecting segment and a rectangular base portion substantially parallel with said top portion, said rectangular portions and said connecting segments uniformly decreasing in aggregate cross sectional area and progressively increasing in resiliency with the distance from said mounting means, said uniformly decreasing area being determined by the formula PX C I where S=stress in pounds per square inch P=load in pounds X=distance in inches from the load to the given cross section C=distance in inches from the neutral axis to the extreme fiber I=1noment of inertia in inches of the given cross section about the neutral axis thereby providing uniform stress in said arm along substantially its entire length upon application of transverse pressure to said contact means.

UNITED STATES PATENTS Esterow Mar. 4, 1930 Larsen May 26, 1931 Bauer Feb. 3, 1942 Stern Oct. 24, 1950 Bowman Nov. 9, 1920 Hauton Oct. 25, 1927 Shure July 31, 1928 Garst Aug. 26, 1930 Esterow Sept. 22, 1931 Segal Mar. 22, 1932 Yerk Sept. 4, 1934 Weisser Apr. 4, 1939 Stenersen Mar. 17, 1942 Bauer Aug. 11, 1942 FOREIGN PATENTS France Nov. 21, 1951 Germany Aug. 24, 1953 Great Brita-in of 1914 Great Britain Dec. 8, 1932 

